As I’ve said before when this came up, I forget where, you could argue both ways for these mastery combinations, but ultimately we went with the reasoning that the Occultist mastery is more attuned to primeval powers and thus a Primalist, while the shaman is more spiritual and thus a Mystic (in a perfect world, Shaman + Berserker would have been a Druid, but we already used that name way back in vanilla GD…something something hindsight 20/20).
These two phrases have been used throughout videogame history and have been interpreted in all sorts of ways. I perfectly understand the logic why you’d want to flip them, but I hope the reverse is also true and why we will not be making the swap.